The long term objective of this work is the enhancement of the sea urchin gamete system as a model for cell and developmental studies. The proposed research will develop procedures to store ovulated eggs in vitro for extended periods of time, from two to four weeks or longer, and still maintain fertilizability and normal development. This would permit experiments that depend on preloading eggs with isotopes to equilibrium, allow expression of injected mRNA and permit multiple experiments on the same batch of eggs. Finally, having long-lived eggs will allow development of methods to ship eggs (as opposed to shipping hard-to-maintain adults), which would expand the pool of researchers using this resource. Sea urchin eggs are normally stored in the ovary for many months. Our preliminary results have demonstrated a significant extension of the lifetime of ovulated eggs by culture under axenic conditions. Because eggs remain viable for many months in the ovary, our experimental approach will involve mimicking the ovarian conditions. The proposed research will examine such parameters as low O2 tension, high CO2, provision of nutrients and antioxidants. When the optimal conditions have been determined, the procedure will be scaled to handle large amounts of egg material. Investigations using the easily studied sea urchin gametes have provided important insights into fertilization, cell division and regulation of gene activity through transcription factors. These findings have led to discovery of similar phenomena in vertebrates such as molecules that control call division (the cyclins), alternate means of calcium release (cyclic ADP ribose) and intracellular pH regulation (Na+-H+ exchangers) to name a few. Enhancement of this resource will expand research on these forms with a resultant increase in our knowledge of general cell and developmental phenomena applicable to all animals.